A broadcasting network according to the related art is divided into a terrestrial broadcasting network and a cable broadcasting network, and information on a specific broadcasting channel is very important in these broadcastings. For example, as an existing audience rating research method used to obtain information on an audience rating, there are a diary method of distributing a booklet in which research contents are printed to viewers to allow the viewers to write their exposure record, an interview research method subdivided into a visiting research method and a telephone research method, a meter research method of attaching a device such as a people meter, an audiometer, or the like, to a television under the consent of a subscriber to automatically record viewing behavior and transmitting the recorded data to a research center through a telephone line, and the like.
In the cases of the diary research and the interview research of the above-mentioned research methods, the research is dependent on a memory of human, such that reliability of the research may be deteriorated, and in the case of the meter research method, installation of the meter may be complicated and expensive, absolute cooperation of a responder is required, data on all of customers receiving services can not be collected, such that reliability of statistical data may be deteriorated.
Korean Patent Application No. 1997-0041880 disclosed a technology of automatically researching the audience rating at each TV broadcasting station. According to this technology, when the TV broadcasting station vertical blanking interval (VBI)-encodes a viewing channel searching command in a TV broadcasting signal to broadcast the TV broadcasting signal and the VBI that is the viewing channel searching command is decoded in a step in which a television receives the TV broadcasting signal, electronic mail (E-mail) including information on currently viewed channels are written and are transmitted to the TV broadcasting station, such that the TV broadcasting station may collect and analyze the received e-mail to utilize the information as sources of the audience rating research.
However, since this method also depends on hands of an operator in collecting and analyzing the e-mail information transmitted from each TV to the TV broadcasting station, this method may also be significantly difficult and troublesome.
The TV broadcasting station should VBI-encode a separate channel searching command in each of broadcasting program data. Therefore, data loss of regular broadcasting may be generated.
Although a sample research may also be conducted by installing a measuring device to a specific subscriber group using the existing method in the Internet protocol television (IPTV) broadcasting, a complete research rather than the sample research may be conducted using more advanced Internet technology without installation of the measuring device to obtain the information in the IPTV broadcasting.
For example, in the case of an audience rating research of a multicast based IPTV, on the assumption that a single IPTV broadcasting channel corresponds to a single multicast group, an audience rating of the corresponding IPTV broadcasting channel may be recognized by recognizing the number of members included in the related multicast group.
However, a current multicast technology recognizes only whether or not a member of the corresponding multicast group is present, but may not recognize how many members are present. Therefore, the present invention suggests an apparatus and method of collecting an audience rating of a specific IPTV broadcasting channel and additional information thereof using a method of recognizing the member of source based multicast tree.